Along with scale expansion and performance enhancement of storage apparatuses, power consumption by the storage apparatuses are growing steadily and the demand for power-saving of the storage apparatuses is rising.
Under such circumstances, a power-saving method by controlling power-on or power-off of a storage apparatus (Japanese Patent Laid-open (Kokai) Application Publication No. 2008-225772) and a method for executing power-saving control on a RAID (Redundant Arrays of Independent Disks) group basis (Japanese Patent Laid-open (Kokai) Application Publication No. 2008-134829) have been suggested in recent years.